A variety of seat belt buckles have been devised to maximize holding capability as well as to improve the cost and ease of manufacture. For example, the U.S. Pat. No. 4,128,924 issued to Herman E. Happel and James R. Anthony discloses a buckle having a pair of reinforcing plates attached to the cover and main body for strengthening the buckle. The buckle includes a spring biased latch urged upwardly to lockingly receive a seat belt tongue. The bottom plate includes a downwardly offset portion at the buckle mouth to provide a guide for the tongue being inserted into the buckle mouth. The same inventors are named in U.S. Pat. No. 4,196,500 which discloses the same type of spring biased latch held captive beneath a block attached between the buckle main body and the buckle cover. An earlier design including a spring biased latch operated by a pivoting handle secured to the buckle main body is disclosed in the U.S. Pat. No. 3,760,467. The U.S. Pat. No. 4,425,688 issued to James R. Anthony and Allan R. Lortz discloses a child belt buckle including a reinforcing plate mounted to a bottom main body and enclosing a spring biased latch with the cover and operator button being located atop the plate.
It is desirable to distribute the force applied to the latch by the tongue in as many directions and over as wide an area as possible. Many of the prior art buckles utilizing reinforcing plate typically distribute the force along the longitudinal axis of the buckle or in the direction of the tongue axis with the result that large forces are applied to the outer walls of the buckle. In the event that the buckle main body is produced of plastic, then failure of the buckle main body is possible. Thus, the plates have been fastened by rivets and assorted fasteners, including plastic projections, to the cover and buckle main body. Disclosed herein is a buckle incorporating a reinforcing plate having support legs which extend perpendicular from the plate and against support surfaces located both in the front and back of the buckle main body thereby transferring some of the force into other areas of the buckle main body. A particular advantage of the design disclosed herein is the positioning of the reinforcing plate atop the tongue mouth of the buckle with the plate legs depending therefrom along the opposite sides of the mouth and then extending partially across the bottom of the mouth defining the mouth perimeter.
Many prior art buckles including the latch buttons are produced from plastic whereas the latch within the buckle is produced from metal. As a result, considerable stress is placed on the button due to the rigidity of the latch. The latch button disclosed herein includes two depending legs position within and against two upwardly extending arms of the latch. The latch arms retain and keep the legs from bowing outwardly as pressure is applied to the button.
In the latest design disclosed herein, a leaf spring is positioned at the aft end of the tongue receiving cavity within the buckle main body to apply withdrawal assist force against the tongue when fully inserted into the buckle. Eject spring have been previously utilized in a variety of buckles. For example, the U.S. Pat. No. 3,523,342 discloses a pair of helical springs located at the aft end of the buckle for urging a split tongue to separate and move from the buckle. Other U.S. Patents cited during the prosecution of the parent application include U.S. Pat. Nos. 3,256,576, 3,605,210 and 4,228,567.